1. Field of the Invention
This invention relates in general to computer-implemented database systems, and, in particular, to multi-level live connection for fast dynamic access to business databases through a network.
2. Description of Related Art
Databases are computerized information storage and retrieval systems. A Relational Database Management System (RDBMS) is a database management system (DBMS) which uses relational techniques for storing and retrieving data. Relational databases are organized into tables which consist of rows and columns of data. The rows are formally called tuples. A database will typically have many tables and each table will typically have multiple tuples and multiple columns. The tables are typically stored on direct access storage devices (DASD) such as magnetic or optical disk drives for semi-permanent storage.
RDBMS software using a Structured Query Language (SQL) interface is well known in the art. The SQL interface has evolved into a standard language for RDBMS software and has been adopted as such by both the American National Standards Institute (ANSI) and the International Standards Organization (ISO). The SQL interface allows users to formulate relational operations on the tables either interactively, in batch files, or embedded in host languages, such as C and COBOL. SQL allows the user to manipulate the data.
The definitions for SQL provide that a RDBMS should respond to a particular query with a particular set of data given a specified database content, but the method that the RDBMS uses to actually find the required information in the tables on the disk drives is left up to the RDBMS. Typically, there will be more than one method that can be used by the RDBMS to access the required data. The RDBMS will optimize the method used to find the data requested in a query in order to minimize the computer time used and, therefore, the cost of doing the query.
The RDBMS software uses various data, including statistics in a RDBMS catalog, during bind time to determine the access paths of SQL statements. A utility, called RUNSTATS, updates the RDBMS catalog with statistics on table spaces, indexes, tables, and columns. Additionally, when an SQL statement is processed during a bind phase, an access path is determined for the statement. The access path is a compiled run-time structure used for executing the SQL statement. The access path is the path the RDBMS uses to get to the data that SQL statements request. For example, an SQL statement might search an entire table space, or it might use an index. The data associated with the access path is stored in the catalog, or optionally in a plan table.
The Internet is a collection of computer networks that exchange information via Transmission Control Protocol/Internet Protocol ("TCP/IP"). The Internet consists of many internet networks, each of which is a single network that use the TCP/IP protocol suite. Currently, the use of the Internet for commercial and non-commercial uses is exploding. Via its networks, the Internet enables many users in different locations to access information stored in databases stored in different locations.
The World Wide Web (also known as "WWW" or the "Web") is a facility on the Internet that links documents. The Web is a hypertext information and communication system used on the Internet computer network with data communications operating according to a client/server model. Typically, Web clients will request data stored in databases from Web servers, which are connected to the databases. The Web servers will retrieve the data and transmit the data to the clients. With the fast growing popularity of the Internet and the Web, there is also a fast growing demand for Web access to databases.
The Web operates using the HyperText Transfer Protocol (HTTP) and the HyperText Markup Language (HTML). This protocol and language results in the communication and display of graphical information that incorporates hyperlinks. Hyperlinks are network addresses that are embedded in a word, phrase, icon or picture that are activated when the user selects a highlighted item displayed in the graphical information. HTTP is the protocol used by Web clients and Web servers to communicate between themselves using these hyperlinks. HTML is the language used by Web servers to create and connect together documents that contain these hyperlinks.
An intranet is an inhouse Web site that serves the employees of an enterprise. Although intranet pages may link to the Internet, an intranet is not a site accessed by the general public.
In conventional systems, a client typically sends a request (i.e., a SQL statement) to a server to access data in a database. A RDBMS at the server processes the SQL statement. The processing includes preparing (i.e., a step in optimizing the execution of the SQL statement) and describing (i.e., a step in optimizing involving processing clauses in the SQL statement) the SQL statement. After processing, the RDBMS executes the SQL statement to retrieve data from a database. The RDBMS then transmits the retrieved data to the client. When the RDBMS at the server receives another SQL statement from the client, the RDBMS prepares, describes, and executes that SQL statement. When the SQL statements are the same or similar, it is inefficient for the RDBMS to prepare, describe, and execute each SQL statement independently.
There is a need in the art for an improved technique for processing SQL statements between clients and servers connected by an Internet or an Intranet.